An electrical control unit (i.e., ECU) mounted to a vehicle such as automobile and two-wheel vehicle is basically disposed in the area which is not affected by water. However, a wiring harness is likely to be disposed through an area which is subject to water permeation (i.e., an area which is affected by water), and thus it should be prevented from water permeation from the wiring harness side into the electrical control unit side. In view of the above, a conventional connector, which can be attached to the terminal portion of an electrical wire of the wiring harness, and is also attached to the electrical control unit, has a terminal fitting, which is connected to the conductor portion of the electrical wire, a connector housing having a terminal receiving chamber (i.e., a terminal receiving space) for receiving the terminal fitting therein, and waterproof body for the prevention of water permeation into the terminal receiving chamber.
Conventionally, heat resistance is needed for waterproof treatment of the wiring harness. In this regard, in order to constitute the afore-mentioned waterproof body, curing resin (e.g., silicon resin) potting approach has been proposed. For example, see JP2009-292898. However, the above curing resin potting approach is time-consuming operation, and the resin used cannot retain its shape alone until being cured. For the reason as set forth above, the resin needs to be flowed into box-shaped container.
Recently, thermoplastic elastomer material which has enhanced heat resistance has been proposed as material for the afore-mentioned waterproof body. For example, see JP 2005-132922 A. However, softening agent should be added to the thermoplastic elastomer material so as to enhance flowability, and filler is added to the thermoplastic elastomer material in terms of morphological stability at an elevated temperature.
Syndiotactic polystyrene-based polymer (hereinafter also called as “SPC”) has remarkably high melting point, compared with polymer other than syndiotactic structure, and is subjected to high temperature during heat forming operation. However, the polymer, due to thermal decomposition occurring during the heat forming operation at the elevated temperature, has a tendency to decrease its molecular weight, thereby decreasing mechanical properties.
Conventionally, in order to mechanical properties decrease due to thermal decomposition during the heat forming operation, phenolic antioxidant and triphosphate, or triphosphate, diphosphate, and phenolic antioxidant have been added to the polystyrene-based polymer. Also, it had been well known to add phosphorus-based compound having a specific structure, and phenolic antioxidant to the composition comprising syndiotactic polystyrene-based polymer, and thermoplastic elastomer. For example, see JP H1-182350.
In the case of using the material as described in the above publications in the preparation of the afore-mentioned waterproof body, adhesiveness to the covering portion of the electrical wire, thermal resistance, flexibility is insufficient, and the waterproof properties of the connector is thus insufficient. To solve the above drawbacks and problems, the present invention provides an improved connector having enhanced adhesiveness to the covering portion of the electrical wire, thermal resistance, flexibility, and waterproofness.